Sustaining wing structure



Oct. 28, 1930. w F. G ERHARDT I 1,779,842

' SUSTAINING WING STRUCTURE Filed July 20 1925 Z'Sheets-Sheet l Hal THE. FLOWSTEEQM QEEQ 0F r-w FHHTE MQHOPLQHE CELLULEL compmason OF muLT'lr Ll-wmi WITH oznme2-r MULTIPLQHE.

x INVENTOR- Oct. 28, 1930. 'v w. F. GERHARDT 1,779,842

SUS TAINING WING STRUCTURE Filed July 20, 1925 2 Sheets-Shet 2 Pic-15 FIE-7:6

u l3 9 I'll o l4- 8 INVENTOYR I Patented Oct. 28, 1930 WILLIAM-FREDERICK G R ARDTQQF mnemonic susmrivme 'wnve swat-dress l. f f

invention relates to sustaining wing cellules, and the primary object ofthe inven- 7 tion is the proper dimensioning-and proportionlngof the sizes of the wings and the spac ing between thew'ings;

My invention includes the'positioning size and -shapeof the wings of a wing cellule'so I that-{maximum efficiency of an airplane or other 3 aircraft, upon which the invention "is appliedgmay be'obtained: This may be done by suitablyclioosing the number of planes,"

' the ehord length; the total sustaining area and-the overall length o-fthe planes, so that p 7 v I governing feature is the height of "the Wing V cellule, sincethe Wing cellnle should ordiis greater than 1 which is the "ultimatelimit to which the present day airplanes-have been carried; The ratio just inentioned-,-'inaccordance 'withfmy invention,- may be increased" above thehitherto known values; so'that-the efiicieney of a wingoellulebuilt in accordance with'my inventiorr'may be increased at least twenty-fivegor' fifty'percent In the" formula "mentioned, F fisf equal ito"the'eross-seetiOn:

of air 'downwardly displacech, or -in-o other Words; the-flow stream-area; N is" the-number of planes in the eellule'whichare spaced one abovethe level of the otherg'bis' the chord length, Athetotal areaof'the wings of the; cellule and'L the overall'length or thelateralh i v we f and in fact absb'lutely neeessary to obtain extent of a plane.

It has been found that ing between the =:wings :of a wing cellule is increased above values which have previously 'been usedand if the chord length is 'decreased and the total number ofplanes of the 'cellule increased over values of presentday construction, an increased 'efliciency' for a argiven' area of Wing surface' Will'result. 'It; has been found that the verticalspaoing be tween adjacent planes in a cellule'dividedby the ehord length should be greater than 1 andibs'tf results are obtained byhavinggthis 4 ;?ratidbetween 2 and 5, and in most'bonstrucif the vertical spac in'gsiand in: the Claims;

airfoil, "InIthis'Yfc aSeQthe sh I x p I stream area-1s approximately" a reetangle due tionsinutherneighborhood of;2 been found that the overall heightof; thecellule divided by the lateral lengthi'of. a -p1ane: of a cellul'e should ;be between-theflimits of ,iIt also; V

These ratios between the spacing between the planes the chord length" and the l'atei'al length of the planes, are governed to some 7 extent 'by the chordlength which should be vention'is the'provision of a method by which the proper sizes and, dimensions and {relativev i positioning of planes be arrived at. 3 I 7 My lnventlon isiof very great advantage of a Wing cellule may for use in manually propelled aircraft or, in

aircraft of the eomparat'i-velylightf anddo vv" poweredtype, althoughiit is'f'not "int'enfild that it'should be restricted to s'uohfi'lnmanually propelled aire'raftgit' is highly. desirable maximum effieieney from face employed. 1

- vention l will. be I'nbreffu'lly discussed in the fo-llbwingispefiifieationt the attached araw- In thQClI'ElWJllgS, F g, scheme for a fin te sectiono to its great length and eornparative'lysiiiall vertical extent. p p

Fig. 2 and Fig. 2 shoe/the flowstream area cally a side elevation and a front elevation,

of a monoplane cellule of a finite length, Figure 2 showing an embodiment where the length is less than the height of the flowstream, and Figure 2 showing the embodiment where the length L is greater'than the height H of the fiowstream.

vFig. 3 and Figure 3 represent diagrammatically a side elevationand front elevation respectively of a multiplane constructed in accordance with my invention and show the extent of the flowstream area in thedotted lines in Figure S p 1 1 w Figures 4 and 4 represent diagrammatirespectively of multiplanes constructed in accordance with present day practice-and show the comparatively small distance between the wings as compared withIthe chord length.

Figures 3 3", and l? 4 showa com- I parison ofthe multipla-ne built in accordance with my invention with ordinary multiplanes or those of the presentday constructionr -Figure-5 is the front elevation-of a manually 'driven airplane of the semi glider type and Figurefi'is aside elevation corresponding to Figure 5;

There are a number of items of airplane performance which itis' the aeronautical engineers task to improve;

(. ig pee c ."(2 Landing speed (V (3) Limiting load Y (WV (4) Ceiling density (1);) c (5) Radius of turn (R (6) Cruising radius (R (7) Cruising endurance (T (8) Minimum power (P The first of these items depends principally upon the drag at zero liftor the profile drag (K,,), and is a complicated function as where C1 and-C are constants.

The secondis afunction' of the maximum 11ft and can be expressed as Where W is the weight of the airplane cellule, W o the remaining weight of the airplane, and F is the How stream, or the" stant. All the others are principally func-' tions of'thecindufced resistance and' of the quantity for example the minimum power (8) is by special arrangement of the cellule, and

and hence .thus improve the"performances (2) to inclusive, while not affecting the speed (1). This isja colllbined aerodynamical and structural problem. The aerodynamical-problem is to secure a large value of the flow stream area (F for any given cellulearea (A). Let usconsider' brieflyh'owthis can be done.-

Fig. 1 shows] a length L of a 'monoplane airfoil of infinite span. It produces reaction j R by virtue of giving'to a layer'of air of height H and speed V a downward deflection angle a and since this reaction is inclined slightly to the vertical, through the lift, B is nearly equal to the total R, the drag R is proportional to BB. Starting from this basis the values of the first mentioned per formances are derived. In this respect reference is made to New aerodynamical conceptions and formulae%lnternational Math. Congress, August 1924,and General theory ofthe constant speed motion ofthe airplane University of Michigan,:1923, dissertations by the inventor;

For any length L, the flow stream'areaF is thus HL. Now this practical height'H is dependent on the'dimensions of the profile, principallyofthe chord (b), secondarily of the camber 'H =mb where m is, a constant for any given camber, thus the flow stream area F (10) F =mbL For a monoplane of finite length i.-'e. a

. length which is large with respect to the chord (small aspect ratio 3 the tip vortices act to constrict the stream to a circular form.

' Hence if the height H =m2 is larger than the span, see F g. 2 we have The intermediate case as shown in Fig. 2 is where the spa-n is larger than the: height,

H /n1). In this case the How stream area: is'

approximately a circle cut of? at the top by limiting lines, distancel-Iapart, or a combination 'of a rectangle and circular segments; l Thus x posed tonget the'maximum, effect .ofthe wing 7 gap lergevat the; samegtime thi-s value. of.

6o .7 e u e loadlng or the'flowstreemjarea F must be- ;:aout .the: flowstreamw area "from be circle of shown; infull lines; Or 1 applying. the: same iwol ldihave for 1snuallivahies of the; gap cord Thiis the probleml is ev feia firsi .,p1aneshould befuse'd" in'prefe'renee to the -With sme11er; chords wings of "larger oember 11 991 l 9 e e jm we $616? he? v oi vthe;.,fl01 ieanti-Q sO ee mult plene.ziet en; .v amped-stem totl t fthequilemismqno is p anesspacedretg pje,: hei ludedv-are aiis :plaf e dsr P 5 I! a (Ni )l Ljendg hefiowstream co es as: megs i hereizrretwvmhrmteti011sAxewhee/hove; V T i v s t eifl w treeni ea'Es in ng l f fi e Place the l g c n e are iq f al t 'm in dim ns. (1; I; L; N)": (b w Q ibeme e t small) as bf'thecelluleii 4 y then the value of K 'stagt tp mcrease 3%;

span being the basi f comparisqmlcanubg1 drag is thecploint 23; Wi i1Oh tilE%I3IggStartdS t2 best *dis osed. ividin 13' 14" moun P y' rincrease 0 6 p o 11 5 v N v [3' height -H.:.There=is house to spe'cuetheplane F f monegthan'hFmb as th'efloizvstrdminolong wh1ch-tellshowthedimensions mustbe -d1s-, increases V I t p The structurahproblemconsistszirrther 'duction of the c ellule weight W for a given area A. This is ac' eomplis hed, see Fig. 5, the above. .y m=.:by t ev decr ase m th .3- anglfiS, t u decra ingrm n'di dedi Q '1 parsl du t h P 1 @Qa zt 'elwiv e f I v the" spar sizes. In other vv ord the cellule as a Wh01e, vvhioh'cen be considered as a unit trus's,- i n ;,deeper the same span area 1 A.- It is, evident from this, thatqift nvve make the number- 015 planes). large and the 1 practice; From Figure: 3? we lsimply stitetch diameter AL to; a especial figure of the form reasoning. .to a: multipiane, we stretchgout then-uflowstream::flfromrthe valueyvvhich it c is smaller than. te ga m noplaee r-el' rq setidey 11 .1 1

tiplane of the same'spa-n. v The aero-structurai improvement is thus brought about; bvyg-these v ponsiderations.

z ndereep. Thus the veliie of b mes-4 4 to :the 1 values-shown .in iFig me 3 2' of prior 'construotions, 'as shovvi f in Fig-1 z e tif he' fl v t ei w f i ar e eih jifi e h d r l l a into-the proper number of planes end dis pose them at proper heightfl Ifthejmulti- 1 high multiplane than the low niultiplaneor I ca11 thejgfloyytstreern v monoplane wek gain the; inoluded" area --between the' ;wings',- A subsidiary reason-' 1s and-henee 1arger values ofm oen-be-mad'e; 0 V

ends. hence the .bquentities Large g ps Should {b used {gain the "Wi1 r e maximum edventage of the inoluded. eree, The advantage which thejinvention shovvsi Em t v a .2 e v .t over prior design, that is in theflowstream rm e PQE-( ,)AE PQI,LdV-l 1 Qn f hfim v 1 r: .1 7;: expressed in terms Qjfa base value 'Which fsnmzlllg,il pyvwer a given evi g s ectimi does not ghgn ith W ill t k (and hence value ofm) and even WIth no.

proportional to monoplane, .v-r'atio of theslejvv o xvvhieh W313:

"Now the power developed'at thepropeller is taken to be 0.9-H P. orq495 :,t,. -/sec.,-'K was taken to be 10, while W; the sum of the'pilots i ht, 5%;?) pl t fuselage, P T P HQ etc.,-allowance(#) totaled 180#. Further "the cellule weight including struts and wires wastakenas 70# that is, an area A of 420 sq. ft. at 0.155 #/sq. ft. Hence WV W 250#. Then-substitutingin formulav ;i-:

the plane were perate at around. '20 ftfiper wseci speed 'and'value offbV,'should not beless' than 30, b, wastakenas' 4 f urther a. span of ft. was assumed as a 'practical hou'sing limit. f Then the numberof planes was A tiim in which m= 16 theiiehdsii,

hence the value of l e/b found by substituting. in formula and solving for V 2 16X1 .5" 4OJ1"{ 40 ]/(7'1)40=3.4ft.= This apparatus is shown in F igs.. 5 and 6. The .value of Fm/A which; could be 1 gotten with the same span area and the same section for. other garrangements is shown in Table, I. Neither the monoplane nor usual multiplane would have suificed- The gain in going'to" they sizes indicated by the invention are more clearly specified by the 'fiowst'ream comparithe table.

in which the' 'cellule is combined with a proymmetry.

through a universal connection 12 at the point A wheel is usedv to launch the machine and the propeller-sustains -thefiight ofthe machine;

. ports the. rear of the-machine and turns with in on the drive wheel (15),? I Itwillbeseen-that the sp ion (-16 and also tabulated in givenby relat I A specific'application-ofthe invention (and example cited) is shown in Figures 5 and 6 peller driven by foot pedalsjthrough appro-' priate gearing:- This specific application was an embodiment of a man. powered glider. The cellule consists. of-a1 lar'ge number of: planes, seven in number, supported'by a truss system composedbf.threeyverticalstruts 2,

.braced to a forward b raciiig'point 3 and a' w r. r i -Po n 4 by we e brace W es 1-}, The 'forward and re rward? points 3 and 4;

are at'the 'extremeends of the fuselage truss 6, which consists of duralmembers-allsituated" the.

central :vertical 1 plane I of A Justin frontjjof'th e line of the struts a1; seat 7 pedals '8, andbevel gear. and sprocket 9 are'fiXed tothe frame in such a manner that a man can operate them comfortably. From the bevel gear extends" a shaft 11 which 3 drives alarge size propeller 13. A chain 14 extendsfrom the sprocket9 to a second sprocketon the main central chassis wheel 15, thus both the fpropeller; andwheel 15 are driven by the pedals. The driven ground A control stick 1 6 m ounted on a swivel uni; vers'al joint connects through suitable wires 1 r I anclp'ulleys tothe rudder :1;8,"elevator l9 and 1 ailerons 20 which: are at the: outer end of one 2. of the "lower planes. JThe' struts 2 areijointed at 21 to permit easy assembly and storage. j The propeller is of thejautomatically'. vari- F able pitch 'typei A uriiversaljoint or fitting 1'- is-suppliediat 'the point'3 to form'lwire pull, propeller bearing, and universal housing combined; There is also a universal'fi'tting at'4' to house the rudder and elevator bearing and l act as wire pulls. The rudder wheel 22 supthe rudder to steer the machine while on the.

igrolindf The wing ave/bea les) whimust barely clear the ground balance the machine a e b w e iacent planes is approximately 2 times the chord length which inthis caseis about 1 feet. ,It' will alsofbe "observed. thatv the total height of the cellule, is about 1/ of the total. U overall length of the wing. This .holds true with the particular wingsection which was 7 2 assumed and: for the given speed and weight. of the. plane f which a weed, 111

} proved to'b'e about 1.4' which is an expression of the efficiency oftheplane and shows-how 130 favorably the eflicien'cy'has' been improved since the corresponding figures for ordinary prior constructions would be less than unity. The following table which has already been mentioned is the comparison of the ef ficiencies of planes built in accordance with my invention with those of prior o0nstruc-' tions Type of plane & fi FmNb L=iii Ft AL Monoplane 3. 1 l. 00 0. 78 Prior multiplene constructions 3. 6 1. 15 0. 90 Improved construction 4. 7 1. 52 1.17

It will therefore be seen that the improvement which has been made by designing the Plane in accordance with the features of novelty herein set forth are of very material advantage and are not only applicable to small planes or manually driven craft, but are also capable of consideration and improving the large type aircraft of today.

I am aware that various modifications may be made in my invention and I do not intend particular form which has been shown for purpose of explanation.

I cla1m:

1. An aircraft having a plural number of fixed double surfaced sustaining planes spaced one above the level of the other, the overall height. of the planes of said sustaining planes divided by the lateral length of ber of planes being greater than 2, the chord length being substantially 1 feet.

5. An aircraft havinga plural number of fixed double surfaced sustaining planes spaced one above thelevel of the other, the. space between adjacent planes of said sustaining planes divided by the sum of their chord lengths being substantially lto 2 and overall height ofthe planes divided by the lateral length of the planes is between whereof I afl'ix mysignature.

In testimony WILLIAM FREDERICK GERHARDT.

that my invention should be restricted to the the planes being to and the vertical spacing of the adjacent planes is greater Y than the sum of their chord lengths.

'2, An aircraft having a plural numberof fixed double surfaced sustaining plaiies spaced one above the level of the other, the

'space between adjacent planes of said susadjacent planes of said sustaining planes divided by the sum of their chord lengths being substantially 1 to 1 the height of the cellule divided by the length of theplanes is substantially and the number of planes I being greater than 2. V

4. A manually propelled aeroplane having a wing cellule formed of a numberof planes placed one above the other, the space between adjacent planes of said sustaining. planes divided by the sum of their chord 7 lengths being substantially 1 to 1 the height of the cellule divided by the length of the planes is substantially and the num- 

